Agree with the above ^. Business is not preferred by most universities in the UK especially Cambridge so you'll put yourself at a major disadvantage by taking it at higher level. Either take another group 3 subject that your school offers that is respected (geography, economics, psychology, history) or take chemistry higher level.
Contrary to what many people think business is actually really hard to get a 7 in due to how subjective marking is so it won't be easy. English is also really hard to get a 7 in as it is also very subjective and requires quite a bit of luck to a 7 in. However, with hard work a 6 should be manageable. Biology: depends on your memorisation skills as it is one of the most content heavy subjects offered by the IBO. If you struggle with memorising big chunks of information/diagrams you'll struggle a lot but if you feel confident in your memorising ability and are slightly scientific you shouldn't face too many issues. The difficulty of maths depends upon your previous experience with maths. If you've done GCSE Maths and are only getting low A's/B's/C's you'll find it challenging as there is a massive jump in difficulty from GCSE to IB. Chemistry should be find granted that you easily pick up concepts and are good at science. Italian ab initio should be manageable if you are able to pick up languages without much issue or have background knowledge in a similar romance language (spanish, french) but be warned that ab initio classes go at a fast pace so you should always stay on top of your work!